Massively Big Picture

The 2011 Japanese earthquake was a defining moment for Mark Simons. The devastating 9.0-magnitude quake and its subsequent tsunami, which took nearly 16,000 lives, spurred efforts around the globe that will shape how nations predict and prepare for future natural disasters and motivated new approaches to basic earthquake science that are applicable to seismic events large and small.

“That earthquake taught us as a community to describe not only what we know, but also what we don’t know,” says Simons, Caltech’s John W. and Herberta M. Miles Professor of Geophysics and JPL’s chief scientist. “People in our discipline were convinced that an earthquake couldn’t occur where it eventually did because they were so comfortable with the model that fit existing data. They didn’t realize there were many other models that would work equally as well—or even better.”

Simons is part of a movement to add precise and panoramic perspectives to previously limited geographic observations, uncovering the underlying processes at scales from granular to global. How do tectonic plates move? How are large ice sheets in Antarctica and Greenland responding to climate change? How do daily tides influence these systems? What happens before, during and after great earthquakes? To what extent can we detect volcano unrest before an eruption? To what extent is it all connected?

“Yes, we’re doing the fundamental science—at the same time, we are effectively the next generation of explorers.”
- Mark Simons

In recent years, the first of what will grow to be a multinational constellation of sophisticated radar imaging satellites has been launched into orbit. Those eyes in the sky are pointed not toward the far reaches of the galaxy, but back at Earth, helping us to answer these questions. In collaboration with JPL, Simons and colleagues are developing the Advanced Rapid Imaging and Analysis (ARIA) program to revolutionize how we observe glaciers and tectonic plates and how we make meaning out of those observations.

The satellites can be directed to take comprehensive snapshots by bouncing signals off a surface using a technique called interferometric synthetic aperture radar (InSAR). Comparing consecutive images reveals secrets about Earth’s movements that are undetectable by eyesight or other tools. Truly capturing—and understanding—this information requires processing tens of terabytes of data—equivalent to the entire printed Library of Congress many times over—per day. And it calls for insatiable curiosity and intellectual mettle. Both are Caltech signatures, shared by the adventurous donors who seek us out.

“There are places on our own Earth where people have never walked—places one or two people have ever laid eyes on,” Simons says. “We have thousands of images of the same spots, and every time we look, we see changes. Yes, we’re doing the fundamental science—at the same time, we are effectively the next generation of explorers, continually discovering our home planet. And that is equally exciting.”

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